Pediatric Anti-NMDA (N-methyl D-Aspartate) Receptor Encephalitis

BACKGROUND: We report the clinical features and course of pediatric patients presenting with anti-N-methyl D-aspartate receptor (NMDA-R) encephalitis. METHODS: Single-center 4-year observational study of pediatric encephalitis associated with NMDA-R antibodies in the serum and/or the cerebrospinal fluid. RESULTS: Three girls with anti-NMDA-R encephalitis were identified. All presented with an acute hyperkinetic movement disorder and seizures, expressive aphasia, and emotional lability requiring inpatient treatment for 1-3 months. Imaging and electroencephalogram findings were nondiagnostic. None had an underlying tumor or ovarian teratoma. All received immune-modulatory therapy, including one or more of the following: high-dose methyl-prednisolone, plasma exchange, intravenous immunoglobulin or mycophenolate mofetil. Two of the three patients relapsed within 6 months of presentation and required retreatment with plasma exchange. All have remained in subsequent remission, with two of the three requiring second-line immunotherapy with rituximab. CONCLUSIONS: Hyperkinetic movements in pediatric patients presenting with acute encephalopathy and prominent psychiatric symptoms should elicit a search for NMDA-R antibodies early in the evaluation. Relapses require aggressive immunomodulatory treatment for remission. This series highlights a unique positron emission tomography scan finding of hypermetabolism in one of the patients that correlated with her clinical symptoms. Recovery and rehabilitation can be prolonged, often taking years after the initial diagnosis. Early identification and treatment is likely to reduce relapses and limit morbidity associated with this potentially devastating but treatable encephalitis.